Recently, a technique termed Open-Flow has been proposed (see Non Patent Literatures 1 and 2). The OpenFlow comprehends communication as an end-to-end flow and exercises path control, recovery from malfunctions, load distribution and optimization on the flow-by-flow basis. The OpenFlow switch, operating as a forwarding node, includes a secure channel for communication with an OpenFlow controller. The OpenFlow switch is operated in accordance with a flow table, addition in or rewriting of which is commanded from time to time by the OpenFlow controller. In a flow table, a set of a matching rule (header field) for matching to a packet header, an action defining the contents of processing and the flow statistics information (Stats), is defined on the flow-by-flow basis (see FIG. 38).
FIG. 38 shows names and contents of actions, as an example, as defined in the Non Patent Literature 2. OUTPUT is an action that outputs a packet at a specified port (interface). SET_VLAN_VID to SET_TP_DST are actions that correct the field of a packet header.
For instance, upon receiving a first packet, the OpenFlow switch retrieves the flow table in search for an entry having a matching rule that matches to the packet's header information (FlowKey). If, as a result of the retrieval, the entry that matches to the incoming packet has been found, the OpenFlow switch applies to the incoming packet the contents of processing stated in an entry's action field. If, as a result of the above mentioned retrieval, no entry that matches to the incoming packet has been found, the OpenFlow switch forwards the incoming packet to the OpenFlow controller, over the secure channel, with a request to the controller to decide a path for the incoming packet based upon its source as well as destination. The OpenFlow switch then receives the implementing flow entry to update the flow table.
Non Patent Literature 3 shows a design statement of a protocol for separating a forwarding element and a control element (ForCES). In 4.3.1.2.2, Transaction Protocol of the Non Patent Literature 3, it is stated that two-phase commit control is to be used for transactional management of a plurality of messages within one forwarding element or across a plurality of forwarding elements.